Multi-Subscriber Identification Module (SIM) communication devices have become increasing popular because of their flexibility in service options and other features. In various types of multi-SIM wireless communication devices, each modem stack associated with a subscription may store information provisioned by its respective network operator in a SIM, which may allow the SIM to support use of various different communication services. For example, various wireless networks may be configured to handle different types of data, use different communication modes, implement different radio access technologies, etc. One type of multi-SIM wireless communication device, referred to as a dual-SIM dual-active (DSDA) device, is typically configured with separate transmit/receive chains associated with each SIM, thereby allowing simultaneous active connections with the networks corresponding to two SIMs.
To enable communications in various networks, a wireless communication device may process data to be transmitted over a radio frequency (RF) air interface, and may perform complementary processing on received RF signals to recover data. In particular, data transmission may involve encoding and modulating the data, generating data samples, and conditioning the samples to generate an output RF signal.
Wireless communication devices typically include a power amplifier (“PA”) to provide high transmit power for the output RF signal. Wireless communication devices typically include a power amplifier to amplify the RF signal to a desired level for transmission, which may depend on how far the user is away from a base station. Next generation wireless systems use a wideband technology that allows for simultaneously transmitting multiple transmit signals, corresponding to different baseband signals, to one or more base stations over a plurality of channels. In some mobile communication devices, this requires transmitting the multiple transmit signals using a single power amplifier.
Since power amplification consumes power, techniques to improve the efficiency of power amplifiers may be implemented in mobile communication devices in order to prolong operation on a battery charge. Such techniques may include adjusting the power supplied to the power amplifier so that the applied power tracks the amount of power in the transmit signal. Adjusting the applied power based on the transmit signal is referred to generally as “envelope tracking” and there are different forms or modes of envelope tracking that can be implemented. Mobile communication devices configured to implement SIMs that are associated with separate RF resources may enable envelope tracking for the power amplifier supporting communications on an active SIM by utilizing transmit components associated with both SIMs. However, such efficiency mode may be disabled when both SIMs are involved in active communications.